6 ACOUSTICS OF SINGING

MUSIC 318 MINI-COURSE ON SPEECH AND SINGING

Science of Sound, Chapter 17Resonance in Singing, MillerThe Science of the Singing Voice, Sundberg

FORMANTS AND PITCH

• IN BOTH SPEECH AND SINGING, THERE IS A DIVISION OF LABOR BETWEEN THE VOCAL FOLDS AND VOCAL TRACT. THE VOCAL FOLDS CONTROL THE PITCH, WHILE THE VOCAL TRACT DETERMINES THE VOWEL SOUNDS THROUGH FORMANT (RESONANCE) FREQUENCIES AND ALSO ARTICULATES THE CONSONANTS

TYPICAL FORMATS OF MALE AND FEMALE SPEAKERS REPRESENTED ON A MUSICAL STAFF.

FIRST AND SECOND FORMANTS OF VOWELS

FORMANT FREQUENCIES

VOWEL /æ/ AS SPOKEN AND SUNG

FORMANT FREQUENCIES OF BASIC SUNG VOWELS

SPECTRUM OF /α/ WITH HIGH AND LOW LARYNX

SINGER’S FORMANT

FORMANT TUNING BY SOPRANOS

F1 AND F2 ARE THELOWEST FORMANTSOF VOWELS /i/, /ά/, and /u/

SOLID LINES ARE THEFIRST 7 HARMONICS OF THE SUNG NOTE

JAW OPENING

INTERVAL TO FIRST FORMANT (SEMI-TONES)

BREATHING AND AIR FLOW

BREATHING

LUNG CAPACITY IN THE YOUNG ADULT AND ITS SUBDIVISION INTO FUNCTIONING VOLUMES. VOLUME OF MALE LUNG IS SHOWN AT LEFT, FEMALE AT RIGHT

SUBGLOTTAL PRESSURE

THE WAY IN WHICH THE VOCAL FOLDS VIBRATE AT A GIVEN SUBGLOTTAL PRESSURE IS ENTIRELY DETERMINED BY THE LARYNGEAL MUSCULATURE. HOWEVER, SUBGLOTTAL PRESSURE IS SIGNIFICANT FOR THE AMPLITUDE AND ALSO, TO SOME DEGREE, FOR THE FREQUENCY OF PHONATION.

AN INCREASE IN LOUDNESS OF PHONATION IS FOUND TO BE ACCOMPANIED BY AN INCREASE IN SUBGLOTTAL PRESSURE

AN INCREASE IN SUBGLOTTAL PRESSURE IS ALSO OBSERVED WHEN THE PHONATION FREQUENCY IS INCREASED

SUBGLOTTAL PRESSURE IN

SINGING

INCREASE WITH SOUND LEVEL

INCREASE WITH FREQUENCY

REGISTERS

RELATIVE STRENGTHS OF HARMONICS IN FEMALE AND MALE VOICES

IN MODAL ANDFALSETTO (MALE)

GLOTTAL MASK WITH INVERSE FILTERING

GLOTTAL WAVEFORMS:

Rates of closure

VOCE VISTAVOCE VISTA IS A FEEDBACK AND ANALYSIS SYSTEM, DEVELOPED BY DONALD MILLER, ESPECIALLY FOR THE SINGING VOICE. IT RECORDS AND DISPLAYS SIGNALS FROM A MICROPHONE AND ELECTROGLOTTOGRAPH

WAVEFORM, SPECTROGRAM, AND SPECTRUM OF A SOPRANO SINGING OCTAVE SCALE. THE CURSOR, AT 4168 ms, MARKS THE 2ND HARMONIC OF F5 AT 1385 Hz WHICH HAS A LEVEL OF -15 dB.

ELECTROGLOTTOGRAPH

AN ELECTROGRLOTTOGRAPH (EGG) IS A PHYSIOLOGICAL SIGNAL RELATED TO THE VIBRATIONS OF THE VOCAL FOLDS.

A MINUTE HIGH-FREQUENCY CURRENT FLOWS BETWEEN ELECTRODES HELD IN PLACE ON EITHER SIDE OF THE LARYNX. THE RESISTANCE BETWEEN THE ELECTRODES DECREASES BY A SMALL AMOUNT WHEN THE VOCAL FOLDS MAKE CONTACT, INITIATING THE CLOSED PHASE OF THE GLOTTIS. THE RESISTANCE RISES AGAIN AS THE GLOTTIS OPENS.

IN SINGING, THE CLOSING OF THE GLOTTIS IS TYPICALLY QUITE ABRUPT AND CAN BE IDENTIFIED BY A SHARP RISE IN THE EGG SIGNAL. IT IS MORE CHALLENGING TO LOCATE THE LESS ABRUPT OPENING MOMENT OF THE GLOTTIS IN THE FALLING SLOPE OF THE SIGNAL.

EGG AND DEGG PATTERNS OF OPENING AND CLOSING GLOTTIS

ELECTROGLOTTOGRAPH

VOCE VISTA FURNISHES THE EGG DISPLAY WITH ONE HORIZONTAL AND THREE VERTICAL CURSORS. THE USER ADJUSTS THE HORIZONTAL CURSOR TO INTERSECT THE EGG SIGNAL AT THE ESTIMATED POINT OF GLOTTAL OPENING. THE MIDDLE VERTICAL CURSOR THEN INTERSECTS THE EGG SIGNAL AT THIS SAME POINT. THE INTERSECTIONS OF THE HORIZONTAL CURSOR WITH THE TWO ADJACENT CLOSING (RISING) SLOPES ARE AUTOMATICALLY SEEN BY THE PROGRAM AS GLOTTAL CLOSINGS. ON THE BASIS OF THOSE CROSSING, THE PROGRAM THEN DISPLAYS:

THE GLOTTAL PERIOD (TIME INTERVAL BETWEEN CLOSINGS)

THE FUNDAMENTAL FREQUENCY (F0)

THE CLOSED QUOTIENT (CQ)—TH PERCENTAGE OF THE GLOTTAL PERIOD DURING WHICH THE GLOTTIS IS CLOSED

THE CRITERION LEVEL (CL)---THE RELATIVE HEIGHT OF THE HORIZONTAL CURSOR AS A PERCENTAGE OF THE TOTAL VERTICAL SPACE

ELECTROGLOTTOGRAPH

WAVEFORM, SPECTROGRAM, AND EGG OF TENOR OCTAVE SCALE TO A4 ON VOWEL /a/

HORIZONTAL CURSOR ON EGG DISPLAY IS SET AT ESTIMATED GLOTTAL OPENING (CL=23%). PERIOD (2.55 ms), F0 (392 Hz), AND CLOSED QUOTIENT (QC=79%) ARE CALCULATED.

CLOSED QUOTIENT

IN HIS BOOK RESONANCE IN SINGING, MILLER MAKES THE FOLLOWING OBSERVATIONS:

A LARGE CLOSED QUOTIENT (CQ) ENABLES INCREASED GLOTTAL RESISTANCE, ALLOWING THE SINGER TO BUILD HIGHER SUBGLOTTAL AIR PRESSURE, AND WITH IT HIGHER SPL

THE VOCAL TRACT WITH THE GLOTTIS CLOSED IS A SIGNIFICANTLY BETTER RESONATOR THAN WITH THE GLOTTIS OPEN

A LARGE CQ BOOSTS THE HIGHER FREQUENCY COMPONENTS OF THE SOUND OUTPUT IN THE DESIRABLE RANGE OF THE SINGER’S FORMANT

ESTIMATING CLOSED QUOTIENT

THE HORIZONTAL CURSOR IS ADJUSTED TO INTERSECT THE EGG SIGNAL AT THE ESTIMATED POINT OF GLOTTAL OPENING. THE MIDDLE VETICAL CURSOR INTERSECTS THE EGG SIGNAL AT THIS SAME POINT. PROGRAM THEN CALCULATES CLOSED QUOTIENT (CQ) AND CRITERION LEVEL (CL) AS FRACTIONS

VALIDATING ESTIMATES OF CLOSED QUOTIENT

ESTIMATES OF CLOSED QUOTIENT MAY BE LARGER THAN A CQ DERIVED BY INVERSE FILTERING OF THE SIGNAL FROM A GLOTTAL MASK. IT IS POSSIBLE THAT GLOTTAL OPENING BEGINS BEFORE THE POINT OF MAXIMUM NEGATIVE SLOPE IN THE EGG SIGNAL. FOR PRACTICAL PURPOSED THE CLOSED PHASE LASTS AS LONG AS THE GLOTTIS IS ACOUSTICALLY CLOSED.

FOR EFFICIENCY, THE MOST FAVORABLE TIMING OF GLOTTAL OPENING IS AT THE FINAL LOCAL MAXIMUM OF THE DOMINANT STANDING WAVE. THE VOCAL TRACT IS CONSIDERABLY MORE EFFECTIVE AS A RESONATOR WHEN THE GLOTTIS IS CLOSED. THUS THERE IS A RESONANCE ADVANTAGE IN A LARGE CQ.